单片机C51外部中断程序答:LOOP1:JB ACC.1,LOOP2 MOV R2,#1 SETB TR0 SJMP LOOP4 LOOP2:JB ACC.2,LOOP3 MOV R2,#2 SETB TR0 SJMP LOOP4 LOOP3:JB ACC.3,LOOP4 MOV R2,#3 MOV P1,#0FFH CLR TR0 LOOP4:LJMP LOOP DELAY:MOV R3,#20 DELAY1:MOV R4,#250 DJNZ R4,DJNZ R3,DELAY1 RET T0ISR:PUSH ACC...